This invention relates to the separation of liquid from a suspension, and more particularly relates to a method, device and assembly for continuously removing liquid from a circulating suspension using a liquid permeable conduit.
Cross flow filtration is a technique which allows the filter element to maintain longer life because the flow of contaminated liquid across the element prevents the accumulation of contaminants and thus keeps it permeable, allowing clean liquid to permeate through the media while the contaminants are concentrated in an ever decreasing volume of liquid.
Since the cross flow concept depends upon the presence of sufficient liquid on the contaminant side of the element to keep the contaminant flowing across the element, it is in general less efficient in terms of the amount of liquid which can actually be separated from the contaminants during a single pass through the filter than other, more conventional filtering techniques. Thus, its use is generally restricted to those applications in which high clarity requirements dictate the use of tight membranes as filter elements. In these applications, the lower separation efficiency is apparently offset by the increased life of the membranes enabled by the cross flow technique.
It is a principal object of the invention to employ the cross flow technique of filtration in certain critical applications which are characterized by the need to treat relatively large volumes of contaminated liquids having relatively low clarity requirements.
It is another object of the invention to provide a filter device and method which are suitable for treating relatively large volumes of contaminated liquid having relatively low clarity requirements.